Advice please

[Simon Pepper]

Hi Everyone,

Firstly I am new today, so please be kind :)

I have decided to take up a new hobby and settled with astrophotography after seeing some amazing videos and images on YouTube. I hope I have chosen wisely with the equipment to start me off, so please be gentle in your responses. as I have already bought them. I opted for wide angle (as I heard that was more forgiving) and also wanted to keep it as lightweight and portable as possible as my back garden has a lot of obstructions.. I am aware that this is not going to be easy and there is a lot of commitment involved both with the cold nights, but also at the computer processing the images (darks, flats and bias). What I have bought so far.

• A sturdy tripod
• William Optics Redcat 51
• Ioptron sky guider pro with ipolar
• Canon 800d / T7i
• T48 copper adaptor

I have been scowering forums in order to answer a few questions and these are around tracking and guiding. Obviously the more exposures you obtain the better the final result. I often see images taken at say 66 x 2 minutes at a given ISO depending on the brightness of the object. what I am unsure of is will my sky guider be able to handle say these exposures or is this when guiding is required? I keep seeing that with a tracker thats well aligned people are saying they are getting 4/5 minute exposures with no star trails. Does this mean that they are only capturing one image at this length or after 4/5 minutes they close the shutter and can go again after a brief pause to let the sensor cool with the next exposure?

I am aware that the iptron has room for guidance, but at 5kg payload I need to be careful with weight. Also as I mentioned I want to keep the weight down for portability. Also I think baby steps are better for a complete novice like me.

Any help would be much appreciated. Clear skies! 

[rickwayne]

I suspect that the only way to really find out will be to experiment. Which, c'mon, will be fun in itself!

I would not expect 240-second exposures off a tracker, certainly not to begin with. 120 seconds with good polar alignment, definitely. I'm sure folks will chime in with their experiences to the contrary but frankly it's a pretty good night for me with my equatorial mount and guiding in both RA and DEC axes if I'm keeping a high percentage of anything longer than 5 minutes.

While it will be super-tempting to try out your beautiful new telescope, you might want to just try some widefield work with a camera lens to start with. That will give you practice in setup/teardown, polar alignment, image acquisition, and processing, and probably some early successes to feed the astrophoto beast within.

That said, don't try for Astronomy Picture of The Day out of the gate. Give yourself permission to play around. If you shoot ten each of 30 seconds' exposure, 1, 2, and 5 minutes, how many of each are good enough by your standards? Except for the camera's read noise, it's a pretty linear thing -- total integration time is total integration time, whether you have lots of short exposures or a few long ones. If your keeper rate is 25% for 5-minute exposures and 85% for 30-second ones, you might wind up with less overall noise at the short end of the spectrum.

If you haven't already picked up a copy of The Deep-Sky Imaging Primer or Making Every Photon Count, I heartily recommend that you do so posthaste. The sort of basic knowledge these books will impart serves as an underpinning for a whole galaxy (sorry) of choices that you make every time you set up and shoot.

And welcome. Boy, are you in for some challenges!

[Simon Pepper]

11 hours ago, rickwayne said:

I suspect that the only way to really find out will be to experiment. Which, c'mon, will be fun in itself!

I would not expect 240-second exposures off a tracker, certainly not to begin with. 120 seconds with good polar alignment, definitely. I'm sure folks will chime in with their experiences to the contrary but frankly it's a pretty good night for me with my equatorial mount and guiding in both RA and DEC axes if I'm keeping a high percentage of anything longer than 5 minutes.

While it will be super-tempting to try out your beautiful new telescope, you might want to just try some widefield work with a camera lens to start with. That will give you practice in setup/teardown, polar alignment, image acquisition, and processing, and probably some early successes to feed the astrophoto beast within.

That said, don't try for Astronomy Picture of The Day out of the gate. Give yourself permission to play around. If you shoot ten each of 30 seconds' exposure, 1, 2, and 5 minutes, how many of each are good enough by your standards? Except for the camera's read noise, it's a pretty linear thing -- total integration time is total integration time, whether you have lots of short exposures or a few long ones. If your keeper rate is 25% for 5-minute exposures and 85% for 30-second ones, you might wind up with less overall noise at the short end of the spectrum.

If you haven't already picked up a copy of The Deep-Sky Imaging Primer or Making Every Photon Count, I heartily recommend that you do so posthaste. The sort of basic knowledge these books will impart serves as an underpinning for a whole galaxy (sorry) of choices that you make every time you set up and shoot.

And welcome. Boy, are you in for some challenges!

Thanks for the reply and I will be sure to check out those books. I am still unsure on the exposures so I will post this again to see if I get some more reply's. Thanks again!

[Stu1smartcookie]

i read this with much interest as i am new to star trackers too ... i have a z61 which pushes the weight a bit once the flattener and the camera is fixed . Like your ioptron my star adventurer has a payload of 5kgs .. i usually go for 30second exposures without any problems ... the problems i do have is actually making sure i have the target in the frame . Even with the night sky app i struggle sometimes . I have also read that its possible , indeed preferable to use a guide cam as this will almost ceratainly increase exposure time . Its all really interesting ..and like Rick said .. its actually fun ( and frustrating ) learning on the job .

Edited April 28, 2020 by Stu1smartcookie